Evolution Review

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Transcript Evolution Review

Evolution Review
History of Major Events
• Earth is 6 billion years old
• Radiometric Dating: a method to establish the
age of materials. Radioactive decay = half life
• First organic compounds
▫ Urey Miller experiment were able to produce
organic compounds by initiating lightening on
water vapor, H2, CH4 and NH3
▫ Development of first cells– Microsphere and
• Transition of chemosynthetic, photosynthetic,
and aerobic
▫ Chemosynthetic used sulfur for energy– Archaea
▫ Gave rise to photosynthetic bacteria –used sun as
energy source---aerobic respiration produces O2
▫ Eukaryotic organisms developed through
endosymbiosis—chloroplasts and mitochondria
▫ Check events that lead to aerobic life. Why did
heterotrophs evolve first?
Modern Evolutionary Theory
• People: Explain their contribution on Darwin’s
• Darwin
Traveled to Galapagos
Studied how animals adapted to environments
Ship: HMS Beagle
Book: On the Origin of Species by means of
Natural Selection
▫ Did Darwin know anything about genetics?
• Evidence for evolution
▫ Fossils
▫ Species variation
▫ Anatomy/embryology
▫ This is very incomplete!!!!!! Check your book and
the ppt. on Charles Darwin.
Species and populations
• Microevolution: change in the collective genetic
material of a population
• Put in some examples here
• Macroevolution: the evolution of a species on a
large scale. Effects the entire species
• Give examples
• Genotype frequencies in a population tend to
remain the same from generation to generation
unless acted o by outside influences.
• Conditions for a stable population
No mutation
No immigration or emigration
Pop. Is large
Selection does not occur
Individual mate randomly
Causes of microevolution
Mutation; give example
Gene flow: give example
Genetic Drift: give example
Nonrandom mating: give example
Natural Selection: give example
Variation in a population
• Sources:
▫ Mutation: random change in a gene passed to
▫ Recombination: reshuffling of genes during
independent assortment and crossing over.
▫ Random pairing of gametes: large number and
fetilizes randomly.
• Single gene traits: determined by a single gene
with two or more alleles Examples
• Polygenic traits: influenced by several genes.
• Patterns of Natural Selection
Be able to draw each type and explain what is
Steps in speciation
• A species is a pop. of organisms that can
successfully interbreed but cannot breed with
other groups.
• Geographic isolation results from the
separation of population subgroups by
geographic barriers.
• Geographic isolation may lead to allopatric
• Allopatric speciation: two groups become
separated geographically which results in
reproductive isolation because of
▫ Genetic drift,
▫ Mutations
▫ Natural selection
• Reproductive isolation: results from the
separation of population subgroups by barriers
to successful breeding.
• Reproductive isolation leads to sympatric
• Sympatric speciation: two population
become reproductively isolated within the same
geographic area.
▫ Each species occupies a different niche
▫ This specialization leads to reproductive isolation.
Rates of Speciation
• Gradualism: species undergo small changes at
a constant rate.
• Punctuated : new species arise abruptly, differ
greatly from their ancestors, and then change
little over long periods.